The present invention relates to a pressure hose, and more particularly to a pressure hose which is advantageously -- but not excessively -- suitable for use in carrying the cooling water for the rotor of a generator.
Pressure hoses for many applications are already well known in the art.
One of these applications requires the use of pressure hoses for supplying cooling water to the cooling channels of stator windings in water-cooled generators. Hoses employed for such purposes can be required to withstand an internal pressure of 15 atmospheres or even higher.
Problems are, however, encountered if in a generator it is not merely the stator which is to be water-cooled, but also the rotor. In many applications the rotors are cooled with air or gas, but it is desirable to use water as a cooling medium for the rotor also. Due to the rotation of the rotor, however, high centrifugal forces develop which cause very high pressures in the hoses that conduct the cooling water in such applications. This means that in a large generator the cooling water hose may be subjected to pressures on the order of 160 atmospheres or even higher. The pressure hoses which are known from the prior art are not capable of withstanding such pressures, being suitable only for pressures to a level of approximately 30 atmospheres. It has been proposed to armor and reinforce these known synthetic plastic hoses with metallic reinforcements to make them more resistant to internal pressures. However, it was found that even this measure could not solve the problem because in the type of application which has been outlined above it is necessary not only that the hoses be able to withstand the pressure, but also that sufficient electrical insulation be present. The metallic armor, however, while serving as a reinforcement, also constituted an electrical conductor extending between the opposite axial ends of the inherently non-conductive hose and was therefore not acceptable.